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Contradictory Statements Made to Foreign Patent Office and Withheld from USPTO Lead to Finding of Inequitable Conduct

In Therasense, Inc. v. Becton, Dickinson and Co.1, the Federal Circuit held that an applicant’s characterization of its own prior art reference in proceedings with the EPO that directly contradicts statements made to the USPTO by the applicant regarding the same reference is material to patentability and can serve as the basis of a finding of inequitable conduct. This case was distinguished from previous cases that held that attorney argument concerning the content of prior art is generally insufficient for a finding of materiality because the representations made to the USPTO were factual assertions provided in declaration and affidavit form.

Plaintiffs Therasense, Inc. and Abbott, Inc. (collectively, “the Patent Owner”) sued defendant Becton, Dickinson and Co. for infringement of U.S. Patent No. 5,820,551, entitled “Strip electrode with screen printing” (the ‘551 patent). The U.S. District Court for the Northern District of California determined that several of the asserted claims were invalid as obvious over the Patent Owner’s own U.S. Patent No. 4,545,382 (the ‘382 patent). The district court also found that the entire ‘551 patent was unenforceable due to inequitable conduct.

The ‘382 patent was cited by the Examiner during prosecution of the application that led to the patent at issue, the ‘551 patent. The claimed glucose monitoring system was directed to a membrane-less sensor, and the Patent Owner argued that the ‘382 patent teaches that electrodes for use with whole blood require a protective membrane. Although the specification of the ‘382 patent provides that “[o]ptionally, but preferably when being used on live blood, a protective membrane surrounds both the enzyme and the mediator layers, permeable to water and glucose molecules,” the Patent Owner submitted a declaration and affidavit that asserted that one of skill in the art would have understood from the ‘382 patent disclosure that a protective membrane was necessary with a whole blood sample. The Patent Owner further asserted that one skilled in the art would read the “optionally, but preferably” language as mere patent phraseology, rather than as a technical teaching. The ‘551 patent issued shortly thereafter.

Several years prior to the submission of the affidavit and declaration during prosecution of the ‘551 patent, the Patent Owner prosecuted the corresponding European application of the prior art reference, the ‘382 patent. Before the European Patent Office (EPO), the Patent Owner argued that the ‘382 patent distinguished over a German reference having a semi-permeable membrane because the protective membrane of the ‘382 patent is a safety measure rather than a permeability control. The Patent Owner further argued that the “optionally, but preferably” statement is “unequivocally clear” that the protective membrane is optional when used with whole blood.

Although the Federal Circuit has previously held that attorney argument concerning the content of prior art is generally insufficient for a finding of materiality,2 the representations to the USPTO during prosecution of the ‘551 patent were not considered attorney argument. Rather, the Federal Circuit determined that the representations were factual assertions provided in declaration and affidavit form, and were thus distinguished from mere attorney argument. By describing the “optionally, but preferably” language of the ‘382 patent as “unequivocally clear,” the Patent Owner’s representations to the EPO directly contradicted the Patent Owner’s sworn statement to the USPTO that one of ordinary skill would have understood the phrase as mere “patent phraseology.” Further, the Patent Owner’s arguments before the EPO that a membrane was not necessary for testing whole blood in vitro contradicted the Patent Owner’s arguments to the USPTO that a membrane was thought to be necessary for the testing of a whole blood sample.

A finding of inequitable conduct requires a showing of an affirmative material misrepresentation or failure to disclose material information coupled with an intent to deceive. Information known by an applicant that refutes, or is inconsistent with, a position taken by the applicant in arguing the patentability before the USPTO is considered material information and should be provided to the USPTO.3 In Therasense, the Federal Circuit concluded that “[a]n applicant’s earlier statements about prior art, especially one’s own prior art, are material to the PTO when those statements directly contradict the applicant’s position regarding that prior art in the PTO.” The Federal Circuit found the lower court’s ruling on intent to deceive the USPTO amply supported, and affirmed the unenforceability of the ‘551 patent due to the Patent Owner’s inequitable conduct.

Although the Federal Circuit makes clear that a finding of inequitable conduct requires a high burden of proof, the Patent Owner in Therasense is “one of those rare case in which a finding of inequitable conduct is appropriate.” To avoid such a finding in light of Therasense, practitioners should continue to monitor submissions made to both domestic and foreign patent offices. Practitioners should consider alerting the USPTO of contradictory statements made in a foreign jurisdiction, especially when those statements directly contradict assertions made to the USPTO in the form of an affidavit or declaration. While attorney argument is generally insufficient for a finding of materiality, erring on the side of disclosure may save a patent from being rendered unenforceable.

This advisory was prepared by Nutter's Intellectual Property practice. For more information, please contact your Nutter attorney at 617-439-2000.

This update is for information purposes only and should not be construed as legal advice on any specific facts or circumstances. Under the rules of the Supreme Judicial Court of Massachusetts, this material may be considered as advertising.